Global Climate Change: Past and Future

1. Global Climate Change: Past and Future Michael E. Mann Departments of Meteorology and Geosciences and Earth and Environmental Systems Institute Director, Earth System Science Center, Penn State University Straub Environmental Lecture Salem, Oregon May 31, 2007

2. `The balance of evidence suggests that there is a discernible human influence on global climate' Intergovernmental Panel on Climate Change (United Nations), Second Assessment Report, 1996

3. `There is new and stronger evidence that most of the warming observed overthe last 50 years is attributable to human activity' Intergovernmental Panel on Climate Change (United Nations), Third Assessment Report, 2001

4. `Most of the observed increase in globally averaged temperatures since the mid-20th century is verylikely due to the observed increase in anthropogenic greenhouse gas concentrations’ Intergovernmental Panel on Climate Change (United Nations), Fourth Assessment Report, 2007

5. OBSERVATIONS

6. Surface Temperature Changes Gray: back to beginning of 20th century Boxes: back to mid 19th century

7. Surface Temperature Changes

8. Surface Temperature Changes

9. Internally Consistent Changes in Other Variables

10. Greenhouse Gases and Warming CO2 Related?

11. ENHANCED GREENHOUSE EFFECT?

12. TREE RINGS

13. CORALS

14. ICE CORES

15. VARVED LAKE SEDIMENTS

16. HISTORICAL DOCUMENTS

17. RECONSTRUCTED GLOBAL TEMPERATURE PATTERNS

18. Reconstructed Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001

19. From “Wikipedia” Reconstructions of Northern Hemisphere mean temperatures for the last 1000 years and instrumental record (black line)

20. Mt Kilimanjaro

21. Mt Kilimanjaro

22. Thompson, L. G., Mosley-Thompson, E., Davis, M. E., Lin, P. N., Henderson, K., and Mashiotta, T. A., 2003, Tropical glacier and ice core evidence of climate change on annual to millennial time scales, Climatic Change, v. 59, p. 137-155.

23. MODEL SIMULATIONS

24. The climate represents a coupled system consisting of an atmosphere, hydrosphere, biosphere, and cryosphere

25. General Circulation Models (GCMs) take into account the full three-dimensional structure of the atmosphere and ocean

26. 1000 1200 1400 1600 1800 2000 CLIMATE FORCINGS Volcanism Solar Natural Crowley, T.J., Causes of Climate Change Over the Past 1000 Years, Science, 289 270-277, 2000.

27. CLIMATE FORCINGS Anthropogenic Industrial Aerosols Greenhouse Gases Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001

28. Simulated Annual Global Mean Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Forced Model simulations

29. Simulated Annual Global Mean Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Forced Model simulations

30. Simulated Annual Global Mean Surface Temperatures Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001 Forced Model simulations

31. Jones, P.D., Mann, M.E., Climate Over Past Millennia, Reviews of Geophysics, 42, RG2002,doi:10.1029/2003RG000143, 2004.

32. Future Surface Temperatures Trends? Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001

33. Model Predictions Climate Change 2001: The Scientific Basis, Houghton, J.T., et al. (eds.), Cambridge Univ. Press, Cambridge, 2001

34. Model Predictions